The present invention relates to a sealed prismatic battery whose output terminal is penetratively fastened to its lid that closes the battery can opening and in which the current collector lead led from the electrode body is connected to the lower end of the output terminal via a lead plate.
JP 2004-14395 A discloses a sealed prismatic battery including a lid that closes the upper surface of the opening of a battery can having a closed-bottom prismatic tubular shape and a negative terminal penetratively fastened to the lid. The negative terminal is fastened to the lid via insulative packing and an insulator arranged on the upper and lower sides of the lid. A lead plate is connected to the lower end of the negative terminal, and a negative electrode current collector lead led from the electrode body in the battery can is welded to the lower surface of the lead plate.
In assembling the battery, the negative terminal, the insulative packing, the insulator and the lead plate are preparatorily fastened to the lid. Then, after the upper end portion of the negative electrode current collector lead is welded to the led plate in a state in which the electrode body is accommodated in the battery can, the lid is fit into the upper surface of the opening of the battery can, and the outer peripheral edges of the lid are seam welded to the peripheral edges of the opening of the battery can.
When the lid is fit into the upper surface of the opening of the battery can after the negative electrode current collector lead is welded to the lead plate, the negative electrode current collector lead is accommodated in a bent state in the battery can. Therefore, the negative electrode current collector lead is easily brought in contact with the inner surface of the battery can by the bending, and it is concerned that the negative electrode current collector lead is short-circuited with the battery can.
According to JP 2004-14395 A, a side of the negative electrode current collector lead is covered with the sidewall of an insulator having a bracket-like cross section shape, by which the negative electrode current collector lead is prevented from coming into contact with the inner surface of the battery can. However, according to JP 2004-14395 A, the lead plate is also covered with the sidewall of an insulator, and the sidewall of the insulator becomes obstructive, making it difficult to weld the negative electrode current collector lead to the lead plate.
In this case, as shown in FIG. 2 of JP H11-25993 A, it is acceptable to form a frame-shaped spacer separately from the lid, previously accommodate the spacer in the battery can and accommodate the negative electrode current collector lead in the spacer after the negative electrode current collector lead is welded to the lead plate. However, there is a problem that the negative electrode current collector lead is pinched between the upper end of the spacer and the lid in fitting the lid into the battery can, possibly causing a short circuit between the negative electrode current collector lead and the lid.